Continuous Alarm Tone

[JohnWF]

RV-12 in flight checking AP74 AP - working fine, air very rough, so I turned off AP; got voice confirmation of AP off.

Then a continuous alarm tone sounded....could not determine its source.

Nothing highlighted
Nothing blinking
No alarm bar
No alarm menu
No voice announcement of alarm
No "Show [page]" button shown
No "silence" button displayed.
Engine analog indications of oil temp/pressue, etc normal
Made immediate landing.
Turned off power to D-180 and recycled power. Tone then gone. Taxi back to hangar..no alarms, engine fine.

What could have been the cause?

 

[JohnWF]

The incident could not be duplicated. When the AP74 is turned off there normally is a "beep" and I guess something just kept it going...no "beep" - just a constant tone..No matter what I did today it could not be duplicated.

A transient oddity. End of problem.

 

[dynonsupport]

Did the menus work normally otherwise? Ie - button pushing caused menus to display normally?

 

[JohnWF]

yes